Recoil Separators for Nuclear Astrophysics studies Manoel Couder

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1 Recoil Separators for Nuclear Astrophysics studies Manoel Couder Institute for Structure and Nuclear Astrophysics University of Notre Dame Joint Institute for Nuclear Astrophysics

2 Outline Nuclear astrophysics Radiative capture kinematics Past, present and future of recoil separator dedicated to radiative capture Conclusions Russbach

3 Radiative Capture Reactions are Present in Most Stellar Reaction Networks From pp-chain to r- and s-process Those involving charged particles (p,g) and (a,g) plays crucial role in Stellar burning e.g. 12 C(a,g) 16 O, and reaction sequence leading to (and competing with) 22 Ne(a,n) 25 Mg Explosions in cataclysmic binaries e.g. 30 P(p,g) 31 S X-ray burts e.g. 15 O(a,g) 19 Ne (and a lot more in the rp-process) In Supernova, production of 26 Al and 44 Ti are influenced by (p,g) rates Part of Nova reaction network Russbach

4 Published Data

5 1) Consistent data. 2) Global fit achieved.

6 Radiatiative capture reaction studies Center of mass energies (a,g): ~0.01 MeV to ~15 MeV (experimentally ~0.3 MeV to ) (p,g): ~0.01 MeV to ~4 MeV (experimentally ~0.2 MeV to ) Direct kinematics With stable ions ( 1 H and 4 He beams) Detection of the gamma s Sometime measurement of the activity of the produced elements LUNA underground laboratory is able to reach lower Russbach

7 Radiatiative capture reaction studies Center of mass energies (a,g): ~0.01 MeV to ~15 MeV (experimentally ~0.3 MeV to ) (p,g): ~0.01 MeV to ~4 MeV (experimentally ~0.2 MeV to ) Direct kinematics With stable ions ( 1 H and 4 He beams) Detection of the gamma s Sometime measurement of the activity of the produced elements Inverse kinematics LUNA underground laboratory is able to reach lower Radioactive beams Stable (to improve efficiency and signal to background ratio) Recoil detection: Coincidence between gamma s and recoil Russbach

8 Radiative capture kinematics a v1 v2 A In the center of mass frame Radiative capture p of a by A forming B B* -p Energy and momentum conservation Russbach

9 Radiative capture kinematics a v1 v2 A Velocity in the lab v g B* v B Russbach

10 Radiative capture kinematics a v1 v2 A Velocity in the lab B* Angular and energy limits Russbach

11 Example DISCLAIMER: OLD EXAMPLE USING EXPERIMENT PARAMETERS OF AN EXPERIMENT THAT RAN AT NOTRE DAME WHILE THE NUMBERS ARE CORRECT THEY ARE NO QUESTIONS REGARDING THE ABILITY TO STUDY THIS SPECIFIC REACTION IN DIRECT KINEMATIC (LENA AND LUNA DID IT!) Russbach

12 14 N(p,g) 15 O proton beam energy: 0.27 to 3.6 MeV Ecm: to MeV Q 7.3MeV For E CM =1.65MeV Eg =8.95 E 15 O ϵ [0.08,0.15] MeV Indirect studies are critical and provide invaluable data. Detection of g OK Since early time of nuclear Detection physics of radiative 15 O KO capture are successfully studied with g detection. However, at lower energies or for certain specific reaction measurement are limited or impossible. Reaction involving radioactive elements are a clear example. Russbach

13 Inverse kinematics 14 N(p,g) 15 O Ecm: to MeV 14 N beam energy: 3.78 to 54 MeV For E CM =1.65MeV Ebeam 24.75MeV Recoil Eg =8.95 E 15 O ϵ [23.59,22.56] MeV Recoil* Beam Target H or He Russbach

14 Inverse kinematics Maximum angular aperture Em g c max arctan 2 E b b Momentum spread p r p * p g 2m E b b 1 Eg c 2m E b b Recoil Recoil* Beam Target H or He Russbach

15 Principles g detector projectiles target projectiles +recoils High efficiency Reduced background for g spectroscopy separation recoils Detection Identification p max recoil arctan p beam Em c 2 p g g b E b Velocity/energy selection focusing and charge selection Ionization chamber Position sensitive detector Time of flight Drawings from D. Schürmann Russbach

16 Recoil separator: Basis principle magnetic dipole electric dipole Wien filter p q =Br 2E q = Ur v 0 = U B Charge selection Mass selection Momentum filter Energy filter Velocity filter Drawings from D. Schürmann Russbach

17 Recoil separator: Design parameters Ratio: DM/M to reject e.g. 14N(p,g)15O DM/M=1/15 Angular acceptance max arctan Target effects to be included Em c 2 g b E b Momentum or energy acceptance p r p * p g 2m E b b 1 Eg c 2m E b b Russbach

18 Some interesting reactions 12 C(a,g) 16 O Holly grail of Nuclear Astrophysics, determine the ratio of 12 C/ 16 O after Helium burning as well as abundance of elements after subsequent evolution D=±31mrad mrad DE=6.5% (~100pmA) 15 O(a,g) 19 Ne Triggers X-ray burst (escape from b limited hot-cno) and contribute to determine their light curve D=±17 mrad DE=3% (~10 11 part/s) 13 N(p,g) 14 O first reaction involving radioactive beam, triggered the development of recoil separators to study radiative capture 18 O(a,g) 22 Ne populate one of the two main ingredient for production of neutron in the s- process D=±40 mrad DE=7.4% Russbach

19 4 He Charge selection Det. 19

20 M. Couder Frontiers

21 Mass separation First order spot size x x x x) a E ( x a) ( x E) ( x m 1 m The beam rejection ( 0 quality 0 strongly E depend on m the width of the recoil spot at the mass selection slits Magnification =0 we want a focus ) =0 we want an achromatic focus Spot size is due to magnification 18 O(a,g) MeV M M ( x m) Recoil Beam Russbach

22 Transmission requirements For absolute cross section, full transmission of the selected charge state is needed Attempt at FMA to study 13 C(p,g) 14 N and 18 O(p,g) 19 F and 18 F(p,g) 19 Ne but limited in transmission Russbach 2015 From: PoS(ENAS 6)058 22

23 DEDICATED DEVICES Russbach

24 CTAG Caltech The availability of post accelerated radioactive beams opened the door to direct cross section measurements For example the 13 N beam of Louvain-la-Neuve allowed the study of 13 N(p,g) in inverse kinematics At Caltech, a recoil separator was constructed out of existing elements of the accelerator lab to demonstrate the feasibility of a recoil separator 13 C(p,g) 14 N 16 O(a,g) 20 Ne 12 C(a,g) 16 O Beam undeflected Russbach

25 European Recoil separator for Nuclear Astrophysics NABONA in Naples study 7 Be(p,g) 8 B Parts moved to Bochum (Germany ) Addition of Caltech Wien filter-> ERNA Dedicated to the study of 12 C(a,g) 16 O g ERNA at the DTL, Bochum, Adapted from a slide of L. Gialanella angular acceptance 32 mrad energy acceptance 10% Russbach 2015 For O at E lab = MeV

26 detector ERNA at CIRCE, Caserta 3MV Pelletron High intensity stable and radioactive ( 7,10 Be) ion beams (possible 26 Al) Recoil Mass Separator 1 ion sources 2 Radiochemistry Plans: 7 Be(p,g) 8 B 12 C(a,g) 16 O 16 O(a,g) 20 Ne 33 S(p,g) 34 Cl 14,15 N(a,g) 18,19 F SHE in nature CSSM gas target accelerator ion beam analysis and purification Slide of L. Gialanella

27 Daresbury Recoil Separator DRS ORNL - HRIBF Angular Acceptance: 6.5 msr (+/- 45 mrad horizontal and vertical) A/Q Acceptance: +/- 1.2 % Velocity Acceptance: +/- 2.5 % Radioactive beam! Energy Acceptance: +/- 5 % A/Q resolution: 1/300 A/Q dispersion: 0.1 %/mm Rejection ~ Overall Length: 13 m Russbach

28 Radioactive beam! Two stages Electrostatic dipoles Rejection ~ Last news: 4 He( 3 He,g) 7 Be With rejection >10 14 Conditioning ED up to +/-230kV NIMB 266 (2008) 4171 Russbach

29 Some specs (for a 15 O(a,g) 19 Ne tune): Optical path length 20.4 m Acceptance - ang.: (+/-20 horiz. & +/- 25 vert.) - velocity +/- 2 % Resolving power: 200 at first stage 600 for second stage Effective mass resolution: ~ 90 after 1st stage, ~ 200 after 2nd stage Russbach

30 PRL 96, (2006) Difficult reaction to study NABONA: ~ Be(p,g) 8 B DRS: ~ F(p,g) 18 Ne ~ Be(p,g) 8 B DRAGON: ~ Na(p,g) 22 Mg ~ Mg(p,g) 24 Al ~ g Al(p,g) 27 Si Eur. 6 Radioactive Phys. J. A 7, beam 303{305 induced (2000) radioactive capture studies in ~17 years!!! Eur. Phys. J. A 42, (2009) Resonances NIMB 266 only (2008) 4171 Resonances energies are critical paramters A lot more induced by stable beams Possibility to study direct capture PRC 81, (2010) Russbach

31 SEparator for Capture Reaction SECAR to be installed at ReA3 Features: Two steps charge state selection Attention to Wien filter design: E and B field homogeneity E/B ratio kept constant with magnetic field clamps and electrode design. Clean-up section additional momentum analysis Radiative capture induced by radioactive beam Based on design of St. George JENSA Gas Jet target: up to at/cm 2 Acceptance: = ±25mrad DE= ±3.1% 15<A<65 Br<=0.8 Tm First stage: Resolving power: 750 Mass resolution: 520 Second stage: Resolving power: 1330 Mass resolution: 775 Design: G.P.A. Berg, M. Couder Russbach

32 SECAR Upgrade path Wien filter: Match hardware design to COSY Expectation Qualitative evaluation of background sources Russbach

33 Rare Isotopes Science Project Korea Slide from Young Kwan Kwon Russbach

34 Yuri Litvinov talk Russbach

35 Measurements with Stable Beams 12 C(a,g) 16 O Total cross section From: PoS(ENAS 6)058 Russbach

36 Measurements with Stable Beams Russbach

37 Summary Dedicated separator for radiative capture A tool developed for radioactive beam used successfully for stable and unstable beam Important tools for direct measurements of astrophysical interests Rely on direct kinematic measurements, on indirect methods For RI beam experiments, need stable beams to commission and tune Can be used during fast beam operation Did not mention target, detection system, diagnostics They are critical ~30 years of separators dedicated for nuclear-astrophysics Strong interaction between stable and RI Beam community New recoil separators are coming Russbach

38 Thanks! ERNA Lucio Gialanella Daniel Schürmann KUTL separator Kenshi Sagara DRS Daniel Bardayan DRAGON Dave Hutcheon SECAR Georg Berg Russbach